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Simon Rendon Arango

Engineer. Creates software. Uses AI cleverly. Occasionally predicts a football match.

Software and AI engineer in London. AI research at Tessl.

Talk to the site

A voice model answers questions about my work out loud and scrolls the page to what it talks about. The microphone starts only when you press Start.

Opens a copy of this page that a model reorders for you.

Experience

Now Jun 2026 to now · London

Tessl

AI Research

  • Core member of Tessl's research team, architecting the software factory: an AI-native platform where coding agents design, build and verify production software
  • Lead model evaluation, benchmarking frontier LLMs to select the optimal model for every agentic task
  • Pioneer context evaluation, quantifying how documentation, specifications and tooling shape agent accuracy, and channel those insights into the product
  • Engineer the code verification layer that safeguards the correctness of agent-generated code before it reaches users

Stack Python · TypeScript · Agents · MCP · LLMs · Evals

  1. Untap

    Software Engineer · Nov 2024 to Jun 2026 · London

    • 90%+ KPI extraction accuracy
    • Client ingestion time −80%
    • RAG and MCP in production
    • Built an LLM pipeline for Untap's private-equity platform that extracts KPIs, targets and cashflows from financial reports with 90%+ accuracy. It cut client data ingestion time by more than 80%
    • Built a RAG system over BigQuery and Gemini, and an MCP server that gives LLMs access to internal tools

    Projects at Untap

    Stack React, JavaScript, Java, Vertex, Gemini, GCP

  2. Glamper

    Software Engineer · Mar 2023 to Sep 2023 · Colombia

    • Bookings up 50%+
    • Serverless backend on AWS
    • LLM itinerary agent
    • Designed and built a serverless backend on AWS Lambda and API Gateway for bookings, payments and users
    • Built an LLM travel agent that plans full trips from the current inventory. Bookings grew by more than 50%
    • Built and maintained the Vue and Nuxt web app

    Stack Vue, JavaScript, Nuxt, Python, AWS

  3. Bancolombia

    Intern Software Engineer · Jul 2021 to Jan 2022 · Colombia

    • Ticket resolution time −35%
    • Cloud migration automation
    • Built Jira and AWS integrations and a React KPI dashboard for the infrastructure team (Nequi). Ticket resolution time fell by 35%
    • Automated cloud migration workflows during the bank’s move from on-premise to AWS

    Stack Python, JavaScript, React, AWS

Projects

Things I build in my own time.

  1. 2026Open source

    An open-source tool that checks structured LLM outputs against expected schemas and values, row by row, and names the reason for every failure.

    Open EvalLensSource on GitHubRead the note: EvalLens

  2. 2026iPhone and iPad app · in progress

    Intus

    An iPhone and iPad app for habits and a journal that I am building. Each morning and evening a model writes a short card from your entries. The text goes to the model only for that call and is not stored.

    Read the note: Intus

  3. 2025 to nowIn progress

    A football model I am building. It will give match probabilities during a game, find similar players and matches, and simulate matches. It is not public yet. The page has a waitlist.

    Visit LFM

Lab

Demos I built that call a model.

  1. Give my agent a job

    Name a small web app. A model writes the code and 8 tests, and repairs the code up to 2 times when a test fails.

  2. Talk to the site

    Ask about my work out loud. A voice model answers from the text on this site and scrolls the page to what it mentions.

  3. Reorder the page

    Type 1 line about who you are. A model reorders the sections of the home page and folds the ones that matter less to you.

  4. Portfolio page from GitHub

    Enter a GitHub username. A model reads the public repos and writes a portfolio page with a link that works for 7 days.

The terminal

A small command line with fixed answers about my work. Type help for the commands. If a line is not a command, a model guesses which page you mean.

All demos

Education

2 degrees in computing. Each one ended with a thesis in machine learning.

  1. Sep 2023 to Sep 2024London

    Imperial College LondonMSc in Computing (Software Engineering)

    • My MSc thesis. A CI job for Nektar++ that flags performance regressions from hardware counters with a variational autoencoder. It cut triage time from days to under 2 hours.

  2. 2018 to 2023Colombia

    Universidad de los AndesBSc in Systems and Computing Engineering

    • My BSc thesis. A model that predicts Formula 1 race winners. About 93% accuracy on race winners, on 70+ seasons of Formula 1 results.

Skills

By area. A heavy name is a skill I use most. A light name is one I have used less.

  1. AI and LLMs

    • Agents
    • Evals
    • RAG
    • LLMs
    • MCP

  2. Languages

    • TypeScript
    • Python
    • JavaScript
    • Java
    • C++

  3. Machine learning

    • Deep learning
    • Reinforcement learning
    • TensorFlow
    • Scikit-learn
    • Pandas
    • NumPy
    • Data visualisation
    • PyTorch
    • Jupyter

  4. Web

    • React
    • Next.js
    • Node.js
    • Express
    • Tailwind CSS
    • Framer Motion
    • shadcn/ui
    • Vue
    • Nuxt.js
    • Design

  5. Cloud and tools

    • GCP
    • AWS
    • Docker
    • CI/CD
    • GitLab
    • HPC
    • Git
    • GitHub

Notes

Essays about my projects and this site.

3 of 4

  1. 3 min read

    Intus

    An iPhone and iPad app I am building for habits and a journal.

  2. 3 min read

    EvalLens

    A small open-source tool that checks structured LLM outputs row by row.

  3. 3 min read

    Who am I?

    A first note. Who I am and what this site is.

All notes

Ask

A chat that answers questions about my work from the text on this site. If the answer is not there, it says so.

Contact

For a question or a collaboration, email me or use the form.

simon@rendonarango.com

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Simon Rendon Arango, London

Set in Sofia Sans and Sofia Sans Extra Condensed. Built with Next.js. Last revised November 2026.